Rear Brake problem (this is going to sound stupid)

[bobwithboobs]

Im having a REALY hard time bleeding my rear brakes  , at first i though well heck! my brakes master cylinder prob bad , so i replaced it(another used one) . and im still having the same problem..  i cant seem to have any resistance what so ever...

ive tried , pumping it , bleeding it (press down , open , close let go )  and nothing seems to do it.. any advice??   im about to call it quits due the frustration.
i have checkked , brake pads (fairly new) , o ring in caliper (fine) , i can see\feel liquid gushing out of the bleeder fitting. i dont see or wont suck any fluid back into the system though (i dont know why) . it does such the fluid back through my clear bleeder line .

ive bled car brakes and hydrolic clutches man of times..
any ideas what im doing wrong?

[Speeddog]

Which bike?

[bobwithboobs]

o sorry , ducati 750 dark 2000

[Bones]

i had the same problem when bleeding my clutch line. then i purchased a vacuum bleeder and it seemed like it was taking FOREVER to bleed the line because the bubbles would never end!  the manual for the bleeder system  said that it is possible for air to escape through the threads when you open the bleeder screw and the fix would be to take off the bleeder screw, add some teflon tape (not covering the hole of course) and then trying to bleed it again. obviously it would let air into the line at first but that seemed to do the trick for me.

[Speeddog]

Try removing the caliper and forcing the pads apart, this will squeeze fluid (and hopefully the bubble) back out through the master into the reservoir.

You're closing the bleeder screw before releasing the pedal, right?

[bobwithboobs]

yep , and it wont even suck anything out of the reservoir.

i dunno i got to try it again once it stop raining  im almost to the point to bring it to a shop... This is bs and should not be so difficult.

[bobwithboobs]

WOOOOOWWWW  my retaining thing on the BMC just sprung away from me and i cant find it.  PLUS the other retaining ring off the old BMC just snapped while removing it.. FLM.

[Bladecutter]

Just out of curiosity, you have removed the brake caliper from the mounting bracket under the swingarm, and turned it right side up before you started bleeding it, correct?

You can't bleed that caliper until the bleeder valve is pointing up.

BC.

[RB]

+1 on removing the caliper. The s2r is notorious for this problem but I see you have a 2000.   Remove the caliper and place a few paint sticks or wood of approximate rotor thickness between the pads while bleeding the line.

A vaccuum bleeder will always draw small bubbles into the vacuum line. A vacuum bleeder is well worth the investment. I got the el cheapo model from horrible frieght, the pneumatic type of course, I hear the hand pump kind break easily. 

[bobwithboobs]

its a 750 dark 2000  so i dont have that problem.. 

But i finally got it bled..  i just took the BMC appart , opened the nipple and plunged the damn thing full till bubbles went away , closed it put the semi-broken  retainer ring back in ( kinda still works for now) and then i just bled it normally. (also this time i put the plastic and rubber grommet thingy back in the reservoir.. i think that might have contributed to my problem.)

I FINALLY have rear brakes..  i dont even think my orginial BMC was bad (but too late now , sum dude ace ace ripped the seal thinking it would stretch liek the o-ring....)

[Airborne]

I'm currently having the same problem as Bobwithboobs, however, none of this advice is working. s2r brakes are a two piston pots right? one of my pistons isnt moving, only the one is. The brakes were fine when I took my swingarm off so I don't think its a mechanical problem, just a bleeding issue.

[Airborne]

also, theres a silver clip that goes in there between the two brake pads. I dont know how to get it back in, it doesnt make any sense.

[Airborne]

ok well i got both the above issues solved, i now have pedal except its only about 1/3 the braking power I'm used to. I can't lock the rear wheel like I used to be able to. I'm guessing I have to keep bleeding.

[RB]

so you removed the caliper and then bled it as described above?

snip...
s2r brakes are a two piston pots right? one of my pistons isnt moving, only the one is. The brakes were fine when I took my swingarm off so I don't think its a mechanical problem, just a bleeding issue.

That sounds like a seized piston, but they are only single pistons IIRC. Usually a piston will seize under pressure and will not return to 'float' when pedal pressure is released therefore burning up your rear brake prematurely.

Your pedal should feel firm when lines are bled correctly, make sure all connections are not wet with fluid.